Dr. Abdallah Hafez Medical Biochemistry - Carbohydrates MCQs

High-yield vocabulary flashcards reviewing key carbohydrate definitions, formulas, reactions, and structures covering monosaccharides, disaccharides, and polysaccharides based on Dr. Abdallah Hafez's Medical Biochemistry MCQ booklet.

Carbohydrates

Polyhydroxy aldehydes or ketones that function primarily as energy storage or structural compounds in living organisms.

Monosaccharide General Formula

The stoichiometric formula for monosaccharides, represented as $C_n H_{2n} O_n$ or $(CH_2O)_n$.

Molisch Test

The general diagnostic chemical test used for the detection of carbohydrates.

Glucose Stereoisomers

Glucose possesses $4$ asymmetric carbon atoms, yielding $2^4 = 16$ possible stereoisomers.

Dextrose

A common alternate name for glucose, which is an aldohexose that rotates plane-polarized light to the right (dextrorotatory).

Levulose

A common alternate name for fructose, a ketohexose that rotates plane-polarized light to the left.

Fetal Blood Sugar

Fructose, which is also the primary carbohydrate utilized by spermatozoa in seminal fluid for energy metabolism.

Deoxyribose

The specific aldopentose sugar found in the structural backbone of DNA.

Ribose

An aldopentose monosaccharide found in RNA and various nucleotides.

Glyceraldehyde

An aldotriose (glycerose) that serves as the simplest three-carbon carbohydrate.

Dihydroxyacetone

A three-carbon monosaccharide that functions as a keto-triose.

Epimers

Isomers that differ in configuration around only a single specific asymmetric carbon atom, such as glucose and galactose (at carbon 4) or glucose and mannose (at carbon 2).

Anomers

Stereoisomers that differ in configuration only at the hemiacetal or hemiketal carbonyl carbon (anomeric carbon), such as $\alpha\text{-D-glucose}$ and $\beta\text{-D-glucose}$.

Anomeric Carbon Atom

The carbonyl carbon atom that becomes asymmetric when the straight-chain form of an open monosaccharide converts into a cyclic hemiacetal or hemiketal ring form.

Mutarotation

The spontaneous change in optical rotation over time until equilibrium is reached, exemplified by $\alpha\text{-D-glucose}$ changing from $+112^\circ$ to $+52.5^\circ$ and $\beta\text{-D-glucose}$ changing from $+19^\circ$ to $+52.5^\circ$.

Carbon-5 Configuration in Glucose

The orientation of the $-H$ and $-OH$ groups around carbon atom 5, which determines whether the sugar belongs to the D or L stereochemical series.

Polarimeter

The laboratory instrument utilized to measure the optical activity and rotation of carbohydrate solutions.

Sorbitol

A sugar alcohol formed by the chemical reduction of glucose or fructose.

Dulcitol

A sugar alcohol produced by the reduction of galactose.

Mucic Acid

An insoluble, dicarboxylic sugar acid yielded by the oxidation of galactose with concentrated nitric acid ($HNO_3$).

Glucuronic Acid

A uronic acid with reducing properties produced by the selective oxidation of glucose at carbon 6.

Gluconic Acid

An aldonic acid produced by the oxidation of glucose at its carbonyl carbon (carbon 1).

Sucrose

A non-reducing disaccharide composed of $\alpha\text{-D-glucose}$ and $\beta\text{-D-fructose}$ linked via an $\alpha-1,2$ glycosidic bond; also referred to as cane sugar or beet sugar.

Lactose

A reducing disaccharide found in milk, composed of $\beta\text{-glucose}$ and $\beta\text{-galactose}$ connected by a $\beta\text{-}1,4$ glycosidic bond.

Maltose

A reducing disaccharide produced by the hydrolysis of starch, glycogen, or dextrin, composed of two glucose molecules joined by an $\alpha\text{-}1\rightarrow 4$ glycosidic bond.

Trehalose

A disaccharide composed of glucose units that acts as a non-reducing sugar.

Invert Sugar

The hydrolytic product of sucrose, formed when sucrose is cleaved into equimolar amounts of free glucose and fructose.

Inulin

A homopolysaccharide fructosan composed of repeating fructose units; it is clinically used in physiological assessments to measure the glomerular filtration rate (GFR).

Glycogen

A heavily branched storage homopolysaccharide of $\alpha\text{-D-glucose}$ in mammalian cells (primarily stored in the liver and muscle) containing branches at intervals of $8$ to $12$ glucose units.

Cellulose

A structural homopolysaccharide in the plant framework composed of $\beta\text{-D-glucose}$ units connected by $\beta\text{-}1,4$ glycosidic linkages.

Amylopectin

The branched component of starch that features branch points along glucose chains at intervals of $24$ to $30$ units.

Dextran

A homopolysaccharide of glucose utilized therapeutically as a plasma substitute to expand blood volume.

Heparin

A sulfated heteropolysaccharide (glycosaminoglycan) that acts biologically as an anticoagulant.

Hyaluronic Acid

A glycosaminoglycan heteropolysaccharide located in joints and connective tissue that provides cushioning and lubrication.

Sialic Acid

The biochemical designation for N-acetylneuraminic acid.